/\/\/\ i have this tv in my bedroom connected to a 5.1.2 receiver and i get everything in ATMOS that the apps support via ARC. i'm daring to gather without owning the soundbar your talking about, that it's a setting in your soundbar. my P-Series is also set to auto (in the audio out) and it works perfectly. make sure your cable is the "certified premium" type since your soundbar passes 4K/HDR or it may not pass those signals at the matching frequencies your tv supports if it passes them at all.
a certified premium cable will have this sticker on the package somewhere, if it doesn't, i wouldn't recommend buying it.
don't spend a fortune, get them from monoprice. i recommend for your system, buy 3 one for each hdmi port, then your covered between tv & soundbar and between tv, soundbar and any 4K/HDR HDCP devices you connect to the soundbar.
also, check pages 10-11 in your manual, is yours setup this way? what have you done on the soundbar side, you seem to be pointing at the TCL, but, haven't said anything about what you've done on the soundbar to verify it's setup properly? have you posted anything in the samsung soundbar thread, if there is one? i'm sure folks have theirs connected to a tv via ARC and are getting ATMOS.
TCL-65R615, 55P605 DV/HDR10 & 49S405 HDR10, Philips BDP7501, BPD7502 UHD Players
Oppo BDP-105D, 105, 93, Marantz AV7702MKII, NR1607. Xbox One S
Emotiva XSP-1, XPA5,UPA2, UPA200 & Mini X Amps, ATV4K 32gb
Speakers, Polk SDA-2, Monitor 10A & 5A, Axiom M80,
VP180, QS8, M2, QS4, ATMOS 7.1.4 & 5.1.2 NYGiants!
Last edited by solarrdadd; 05-08-2020 at 08:12 AM.
Reason: inserted picture and more info